For sure; better design would move most supply lines to interior walls. However, most owners of standalone homes want to be able to look out a window situated a

For sure; better design would move most supply lines to interior walls. However, most owners of standalone homes want to be able to look out a window situated above their kitchen sink. It's possible to have supply lines sticking out of the floor, but that complicates inspection and cabinet installation and also it sucks to have to search for one's undersink supplies behind those pipes. Another factor, in concrete slab construction, is that we want drain lines to be as short as possible, because even though it's possible to get those correct before the pour it doesn't always happen. Concentrating fixtures in one corner of the house tends to force supply lines into exterior walls. Maybe I should hire better plumbers, and maybe I should live where it doesn't get cold, but until then maybe I should just use PEX.